Smoke or gas producing composition

ABSTRACT

A smoke or gas-producing compound usable even in spin stabilized grenades, consisting of a gas producing liquid (Ti Cl4) absorbed in a powder with great inner porosity. The grain division lies between 0.125 - 6 mm and the powder is under graded.

United States Patent Andersson [54] SMOKE OR GAS PRODUCING COMPOSITION Rolf Andersson, Tamnarragen 26, Johanneshov, Sweden Filed: March 31, 1970 Appl. No.: 24,204

Inventor:

U.S. Cl ..252/305, 149/21, 149/109 Int. Cl. ..C09k 3/30 Field of Search... .....252/305, 306, 190, 315, 259.5;

[ 51 June 20, 1972 [56] References Cited UNITED STATES PATENTS 1,426,338 8/1922 Sperry ..252/305 3,402,129 9/ l 968 Tatyrek ..252/305 Primary Examiner-John D. Welsh Attorney-Munson & Fiddler [57] ABSTRACT 7 Claims, 1 Drawing figure PATENTEBwnzo m2 CDEF A II rflli I m I 1 .01 I! II B H Hy w v m m u n ,a m u mm a u Mesh Width in mm. 1

SMOKE OR GAS PRODUCING COMPOSITION FIELD OF THE INVENTION This invention is in reference to a smoke or gas-producing compound wherein the compound consists of a smoke or gas producing liquid such as titanium tetra chloride and this compound is thickened by being wholely or partially absorbed by a highly absorbant powder with high porosity and principally open pores. Such a compound can to advantage, because of its inner friction. even be used in spin stabilized smoke or gas grenades.

BACKGROUND OF THE INVENTION It is previously known that liquids can be thickened when, under certain conditions, absorbed in powder formed compounds such as calcium and silicon oxides.

Under the right condition between an absorbing powder and a smoke producing liquid a relatively compact smoke compound can be formed, which can be used as a filling in socalled smoke ammunition. When the grenade is detonated the grenade casing bursts and the smoke compound is cast out. The absorbed smoke compound comes then in contact with the airs humidity, whereby a powerful smoke development begins.

The quantity of smoke liquid which is absorbed is dependant upon, among other things, the absorbing powders total surface area. Therefore a compound consisting of small particles has a large external surface and should therefore bind large amounts of the smoke liquid. The largest instantaneous smoke development comes therefore from a very finely powdered and relatively single grained powder with a grain dimension which for the most part is smaller than 0.01 mm. Such a compound is very sensitive to such things as over-doses of liquid or violent external shock or vibration stresses. This can cause the liquid to separate from the powder thus the internal friction is decreased a great deal. Such a compound can not in this condition be used in spin stabilized projectiles.

A smoke compound with the best possible qualities should contain a maximum amount of the smoke liquid, while at the same time the compounds internal friction must be great enough to resist the stresses created in a spin stabilized grenade.

The smoke development shall furthermore begin immediately upon the shell burst. The smoke producing time shall be long and the amount of smoke shall be sufficient to have a blanketing effect.

Furthermore, the smoke compound should be easy to prepare and pack in the grenade.

A smoke compound as presented according to this invention satisfies the mentioned qualities and contains a specially gradated high absorbant powder in which the smoke liquid is absorbed, The most significanted characteristics for a smoke compound according this present invention are given in the following claims.

An important consideration so that the powder and smoke compound will satisfy the above mentioned demands is that the powder has a sufiicient inner or internal friction, which is achieved by grading the dry compound so that it contains both the smaller and larger particles. The friction is increased if the grains has an irregular. preferably cornered external form.

The maximal instantaneous smoke effect with a long smoke producing period is achieved when the grains are highly porous with a large inner micro-porosity plus that the gradations are chosen so that the total absorbing surface is maximal or approaching maximal.

It has been shown that the smoke production period increases if the powder's gradations are chosen with a surplus or larger particles with a greater inner porosity.

As explained above, the smoke production begins after the grenade detonation and this smoke production is created from the compounds or grains total exposed surface. This, the smoke caused from the external surface of the grain stops after a short time and the continued smoke development is created by the liquid absorbed in the porous grains. The smoke production time is therefore a function of the grains (micro) pores absorbed liquid so that the greater number of pores lengthens the smoke productions duration.

The smoke productions duration in time plus even the grenades filling operation is influenced by the dry powder's humidity level. Therefore the space between the grain and the grains pores is closed when, for example, titanium tetra chloride reacts with the inclosed humidity and Ti(OH precipitates. The humidity level must therefore be minimal and should be under 10 weight percent.

All air or other gases inclosed in the dry compound make the smoke liquids absorption more difficult. These encased gases should therefore be removed, for example, through vacuum treatment of the compound before or in connection with the grenades filling. The filling of the smoke liquid should also be done under a vacuum.

The filling of the grenade is made easier by the fact that the dry powders gradations are chosen so the powder can directly be put into the grenade. This is made easier when the powder is under gradiated, that is to say, it has a deficit in the finer particles. The powders absorption ability shall, after the powder is packed (for example through vibration) be so great that the smoke liquid can directly be poured into the dry compound and the smoke liquid shall after a short time be equally distributed over the compounds total volume Concerning the absorption materials gradation, the attached diagram shows a figure over the border curves for the grain size divisions (gradation curve) for the absorption material according to this invention. The curves exhibit graphically the materials gradations in a dry condition and is in reference to material that is sifted on a metal sleeve with a squared mesh and a free mesh width which gradually increases from 0.125 mm to 6 mm.

The grain division curve is given by the sifting result whereby the sieves free mesh width is given on the abscissa and the weight of the sifted material on the ordinate. The abscissa has been drawn on a logarithmic scale which shows the finer materials grain size more clearly. The ordinate that gives the size of the sifted material is given a linear scale. The grain division curve is based on the following sifting procedure. The sifting is done with vibrations which give a horizontal as well as vertical movement.

The weighted sift material is given at percent. After the sifting the sifted material from each sifting is weighed and the percent of the total amount calculated. Thereafter the total amount of sifted material per sift is drawn on the divisions diagram. The lowest percent of the sifted material passed the sieve at the finest mesh and the greatest amount passed through at the largest mesh. By this method the sift curve can never have a negative inclination.

The material according to this invention has a grain size between 0.125 and 6 mm, and the materials grain division of border curves are A and B as in the diagram.

The material according to the diagram can to a small degree lie outside the curves A and B at their end points and this is illustrated through the dolled lines of the curves.

Curve A (the straight line) shows approximately the upper border or limit for a sifted compound with a large grain size. The materials inner friction is greater than for the material according to curve B (see below) while the smoke producing period is longer.

For instantaneous smoke development is though equally a fast as the material in curve B, even if the smoke compound absorbed smoke liquid volume is smaller.

Curve B (the straight line) shows approximately the lower border or limit for a fine grained compound (grain size 0.25 mm). This material has a high absorption capability and gives an intensive but relatively short smoke development.

Curves C, D, E and F are examples of grain divisions for different materials that have been tested and have given good results.

Several examples of suitable absorption materials exist and as a matter of fact the absorption compound can be made of an organic material such as high porosity carbon, which has a large internal pore surface and principally open pores. Even a synthetic material or a natural material that is in itself porous and light can be used. The material must not be more than 15 percent soluble in 30 percent chlorohydric or sulphuric acid and the grain size divisions shall lie between the grading curves A and B as given in the diagram.

More concrete examples of a suitable material are:

a. calcium silicate clinker (highly porous culm cinder) with a volume weight, that dependant upon the grain gradation and production method, can lie between 0.5-l .3 kg/liter;

b. clinker (cinder) which is obtained by the heating to a high temperature ofordinary field clay;

c. carbon or carbon cinder;

d. porous cinder or ash obtained from vulcanic material and consisting of at least 45 percent SiO and the rest principally ofCaO. M Fe O plus alkaline oxides.

The high absorptive powder which is used can possibly be under graded so that 85 percent weight has a grain size larger than 0. I25 mm. As a matter of fact it can to advantage consists of high porous carbon with a density under 700 g/liter and with an internal porous surface that is larger than 120 m /g (b.e.t.) plus with a purity of at least percent pure carbon. The carbon can consist of active carbon.

The b.e.t. method is used to measure the porosity in the powder form of the material. This method is described in such books as, for example, Absorption, Surface Area and Porosity" of 8.1. Gregg-Ping 1968) and The Surface Chemistry of Solids" (1961) of SJ. Greggs. The method in question can briefly be described as such:

1. A certain amount of powder for example active carbon is dryed carefully.

2. A certain amount of nitrogen gas (there are even other gases) is leaked into the test chamber so that a nitrogen pressure is achieved.

3. The powder is then frozen down to the nitrogen freeze point I95 C.

4. The nitrogens mono layer is measured beside the actual gas pressure by weighing.

In the case that the powder is made of calcium silicate clinker of a type of highly porous cinder, the volume weight should be under 1.3 kg/liter and with an internal pore surface which is larger than the powders visible surface and its chemical ling analysis is:

SiO 36 45 percent, CaO 43 50 percent, A1 0 2.4 percent, FeO 0.2 0.5 percent.

Should the material be of a vulcanic nature it shall consist of: SiO at least 40 percent, Fe O at least 9 percent, CaO at least 8 percent. and the remainder principally of A1 0 MgO plus alkaline oxides.

When it concerns the relationship between the liquid weight and the powder weight it is suitable to let the liquids weight make up at least two times the dry powders weight plus that the liquids volume makes up at least 40 percent of the prepared compounds volume.

ln the above description, the smoke producing substance is suggested as titanium tetrachloride (Ti C1,) but even other substances can be used, for example silicon tetra chloride (Si C1,) chlor sulphonic acid (HCl S0 stanic chloride (Sn C1,). Examples of gas producing substances such as the following battle gases. which in a pure state and at C. are liquids are sarin. tabun. soman, plus the gases under the general classification as F-gases.

This invention is of course not only limited to the examples stated above but can be modified within the scope of the following claims. As a matter of fact the absorption material can even include general porous materials that satisfy the demands of this invention and which are not to any degree chemically effected by actual smoke or gas producing liquids and that the division curve lies within the outline for border curves A and B. Even somewhat closer curves A and B are possible, viz.

such curves that lie between 0.2 3 mm.

This invention is suitable for different types of smoke ammunition such as artillery projectiles, grenade throwing projectiles, rocket heads, and bombs. The suggestion according to this invention that the grain should be cornered is of greatest service in spin stabilized projectiles in that it provides a higher inner friction. ln non-rotating projectiles such as airplane bombs the grain serves as a delay body in that the liquid inside the grains pore successively evaporates within a time period dependant upon the grains size and porosity. The instantaneous smoke effect is achieved by the evaporation of the smoke liquid which has been absorbed on the grains outside. When it concerns the liquids viscosity it should be approximately that of water or maximum 2.5 at +20 C. A lower viscosity than 1.0 is advantageous because the grains absorption capacity increases with a lower viscosity.

What is claimed is:

l. A smoke or gas producing composition possessing sufficient internal friction co-efficient for use in stabilized smoke or gas grenades, composed of a smoke or gas producing liquid of the class including titanium tetrachloride, silicon tetra chloride, chlor sulphonic acid, stannic chloride. sarin. tabun. soman and in other gases in the general classification of F- gases, and an absorbent powder of inorganic material. in which composition the powder component comprises at least 40 percent by volume characterized in that the powder comprises a mixture of grains ranging in size between 0.125 mm and 6 mm and that at least percent by weight of the grain mixture is composed of grains ranging in size between 0.125 mm and 6 mm according to a predetermined coefficient of internal friction.

2. A composition according to claim 1, characterized in that the humidity level of the powder to be mixed with the smoke producing liquid is less than 10 percent by weight.

3. A composition according to claim 2, characterized in that the powder is made up of high porosity carbon, with a density under 700 g/liter and with an internal pore surface that is larger than I20 m /g (b.e.t.) and with a purity of at least 75 pure carbon.

4. A composition according to claim 3, characterized in that the carbon consists of active carbon.

5. A composition according to claim 1, characterized in that the powder comprises of calcium silicate clinker of a highly porous cinder with a volume weight that is under l.3 kg/liter and with an internal pore surface that is larger than the external visible surface of the powder and which chemical analysis formula is: SiO 36 45 percent, CaO 43 50 percent, M 0 2 4 percent, FeO 0.2 0.5 percent.

6. A composition according to claim 1 characterized in that the powder is made of material of a vulcanic nature which is at least 40 percent SiO at least 9 percent F8 0,, and at least 8 percent CaO and the remainder principally Al O MgO plus alkaline oxides.

7. The process of making a composition according to claim 1, characterized in that air or other gases completely or partially have been removed from the pores in the dry powder and from the voids or spaces between the powder grains, by subjecting the powder before or during the mixing with the smoke producing liquid to a partial vacuum 

2. A composition according to claim 1, characterized in that the humidity level of the powder to be mixed with the smoke producing liquid is less than 10 percent by weight.
 3. A composition according to claim 2, characterized in that the powder is made up of high porosity carbon, with a density under 700 g/liter and with an internal pore surface that is larger than 120 m2/g (b.e.t.) and with a purity of at least 75 pure carbon.
 4. A composition according to claim 3, characterized in that the carbon consists of active carbon.
 5. A composition according to claim 1, characterized in that the powder comprises of calcium silicate clinker of a highly porous cinder with a volume weight that is under 1.3 kg/liter and with an internal pore surface that is larger than the external visible surface of the powder and which chemical analysis formula is: SiO2 36 - 45 percent, CaO 43 - 50 percent, Al2O3 2 - 4 percent, FeO 0.2 - 0.5 percent.
 6. A composition according To claim 1 characterized in that the powder is made of material of a vulcanic nature which is at least 40 percent SiO2, at least 9 percent Fe2O3, and at least 8 percent CaO and the remainder principally Al2O3, MgO plus alkaline oxides.
 7. The process of making a composition according to claim 1, characterized in that air or other gases completely or partially have been removed from the pores in the dry powder and from the voids or spaces between the powder grains, by subjecting the powder before or during the mixing with the smoke producing liquid to a partial vacuum 